System and method for operating an inverter-based resource in grid-forming mode (GFM) for enhanced stability
A method for operating a renewable energy source having an inverter-based resource (IBR) system connected to a power grid includes: operating the IBR system as a virtual synchronous machine (VSM) in grid-forming mode (GFM) control; deriving a power error signal (P ERR ) between an actual real power output (Pfbk) from the IBR system and a power reference (P ref ); with an inertial power regulator, using the power error signal (P ERR ) to generate a power angle command signal received by a voltage regulator; with the voltage regulator, generating an x-direction current command (IRCmdx) signal and a y-direction current command (IRCmdy) signal that are both received by a current regulator; and generating and adding a delta x-direction current (ΔIRx) component to the (IRCmdx) signal.
1 . A method for operating a renewable energy source having an inverter-based resource (IBR) system connected to a power grid, wherein the method allows for tuning an active power response of the renewable energy source, the method comprising:
operating the IBR system as a virtual synchronous machine (VSM) in grid-forming mode (GFM) control;
deriving a power error signal (P ERR ) between an actual real power output (P fbk ) from the IBR system and a power reference (P ref ) representing a desired power output of the IBR system;
with an inertial power regulator, using the power error signal (P ERR ) to generate a power angle command signal received by a voltage regulator;
with the voltage regulator, generating an x-direction current command (IRCmdx) signal and a y-direction current command (IRCmdy) signal that are both received by a current regulator; and
generating and adding a delta x-direction current (ΔIRx) component to the (IRCmdx) signal, thereby providing an additional means of tuning the active power response.
2 . The method according to claim 1 , wherein the renewable energy source is a wind turbine power system.
3 . The method according to claim 2 , wherein the IBR system includes a doubly-fed induction generator (DFIG).
4 . The method according to claim 1 , wherein the renewable energy source is a battery energy storage system (BESS).
5 . The method according to claim 1 , wherein the renewable energy source is a solar power system or a hydro power system.
6 . The method according to claim 1 , wherein the method minimizes effects from transient power events on the power grid, the transient power events including are any one or combination of; a low voltage event, a high voltage event, a multi-fault event, a phase jump event, or a frequency shift event.
7 . The method according to claim 1 , wherein the delta x-direction current (ΔIRx) component is derived as a function the power error signal (P ERR ) input to the inertial power regulator.
8 . The method according to claim 7 , wherein the function is according to:
Δ
IRx
=
[
P
ERR
2
IRx
(
)
*
P
ERR
]
=
(
kp
/
(
1
+
sT
)
)
*
(
P
ERR
/
Vmag
)
Wherein:
kp=a proportional tunable gain
T=Tunable filter time constant
P ERR =Per unit power error=P ref −P fbk
Vmag=grid voltage magnitude.
9 . The method according to claim 8 , wherein minimum and maximum limits are placed on ΔIRx, and wherein the limits and the kp proportional tunable gain are constant or are adjusted dynamically upon detection of transient power events on the grid.
10 . A renewable energy source connected to a power grid, comprising:
an inverter-base resource (IBR) system;
a controller for controlling the IBR system, the controller comprising a processor configured to perform a plurality of operations, the plurality of operations comprising:
operating the IBR system as a virtual synchronous machine (VSM) in grid-forming mode (GFM) control;
deriving a power error signal (P ERR ) between an actual real power output (P fbk ) from the IBR system and a power reference (P ref ) representing a desired power output of the IBR system;
with an inertial power regulator, using the power error signal (P ERR ) to generate a power angle command signal received by a voltage regulator;
with the voltage regulator, generating an x-direction current command (IRCmdx) signal and a y-direction current command (IRCmdy) signal that are both received by a current regulator; and
generating and adding a delta x-direction current (ΔIRx) component to the (IRCmdx) signal, thereby providing an additional means of tuning the active power response.
11 . The renewable energy source according to claim 10 , wherein the renewable energy source comprises a wind turbine power system, and wherein the IBR system comprises a doubly-fed induction generator (DFIG).
12 . The renewable energy source according to claim 10 , wherein the renewable energy source comprises a battery energy storage system (BESS).
13 . The renewable energy source according to claim 10 , wherein the renewable energy source comprises a solar power system or a hydro power system.
14 . The renewable energy source according to claim 10 , wherein the plurality of operations comprises deriving the delta x-direction current (ΔIRx) component as a function the power error signal (P ERR ) input to the inertial power regulator.
15 . The renewable energy source according to claim 14 , wherein the function is according to:
Δ
IRx
=
[
P
ERR
2
IRx
(
)
*
P
ERR
]
=
(
kp
/
(
1
+
sT
)
)
*
(
P
ERR
/
Vmag
)
Wherein:
kp=a proportional tunable gain
T=Tunable filter time constant
P ERR =Per unit power error=P ref −P fbk
Vmag=grid voltage magnitude.
16 . The renewable energy source according to claim 15 , wherein minimum and maximum limits are placed on ΔIRx, and wherein the limits and the kp proportional tunable gain are constant or are adjusted dynamically upon detection of transient power events on the grid.